U.S. patent application number 13/475574 was filed with the patent office on 2013-11-21 for methods for forming resist features, patterns in a resist, and arrays of aligned, elongate resist features.
This patent application is currently assigned to MICRON TECHNOLOGY, INC.. The applicant listed for this patent is William R. Brown, Anton J. deVilliers, Ho Seop Eom, Lijing Gou, Kaveri Jain, Adam L. Olson. Invention is credited to William R. Brown, Anton J. deVilliers, Ho Seop Eom, Lijing Gou, Kaveri Jain, Adam L. Olson.
Application Number | 20130309605 13/475574 |
Document ID | / |
Family ID | 49581568 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130309605 |
Kind Code |
A1 |
Jain; Kaveri ; et
al. |
November 21, 2013 |
METHODS FOR FORMING RESIST FEATURES, PATTERNS IN A RESIST, AND
ARRAYS OF ALIGNED, ELONGATE RESIST FEATURES
Abstract
Methods of forming resist features, resist patterns, and arrays
of aligned, elongate resist features are disclosed. The methods
include addition of a compound, e.g., an acid or a base, to at
least a lower surface of a resist to alter acidity of at least a
segment of one of an exposed, acidic resist region and an
unexposed, basic resist region. The alteration, e.g., increase or
decrease, in the acidity shifts an acid-base equilibrium to either
encourage or discourage development of the segment. Such "chemical
proximity correction" techniques may be used to enhance the acidity
of an exposed, acidic resist segment, to enhance the basicity of an
unexposed, basic resist segment, or to effectively convert an
exposed, acidic resist segment to an unexposed, basic resist
segment or vice versa. Thus, unwanted line breaks, line merges, or
misalignments may be avoided.
Inventors: |
Jain; Kaveri; (Boise,
ID) ; Olson; Adam L.; (Boise, ID) ; Brown;
William R.; (Boise, ID) ; Gou; Lijing; (Boise,
ID) ; Eom; Ho Seop; (Boise, ID) ; deVilliers;
Anton J.; (Boise, ID) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jain; Kaveri
Olson; Adam L.
Brown; William R.
Gou; Lijing
Eom; Ho Seop
deVilliers; Anton J. |
Boise
Boise
Boise
Boise
Boise
Boise |
ID
ID
ID
ID
ID
ID |
US
US
US
US
US
US |
|
|
Assignee: |
MICRON TECHNOLOGY, INC.
Boise
ID
|
Family ID: |
49581568 |
Appl. No.: |
13/475574 |
Filed: |
May 18, 2012 |
Current U.S.
Class: |
430/270.1 ;
430/322; 430/325; 430/326 |
Current CPC
Class: |
G03F 7/322 20130101;
G03F 7/11 20130101; G03F 7/38 20130101; G03F 7/325 20130101 |
Class at
Publication: |
430/270.1 ;
430/322; 430/326; 430/325 |
International
Class: |
G03F 7/20 20060101
G03F007/20; G03F 7/004 20060101 G03F007/004 |
Claims
1. A method of forming a resist feature, the method comprising:
forming a patterning resist above a marker material supported by a
base material; selectively exposing the patterning resist to define
at least one region of exposed resist and at least one region of
unexposed resist, an acidity of the at least one region of exposed
resist exceeding an acidity of the at least one region of unexposed
resist; and diffusing a compound from the marker material into the
patterning resist to alter at least one of the acidity of a segment
of the at least one region of exposed resist and the acidity of a
segment of the at least one region of unexposed resist.
2. The method of claim 1, wherein: forming a patterning resist
above a marker material comprises forming a patterning resist above
an acidic marker material; and diffusing a compound from the marker
material into the patterning resist comprises diffusing acid from
the acidic marker material into the patterning resist to increase
one of the acidity of the segment of at least one region of exposed
resist and the acidity of the segment of at least one region of
unexposed resist.
3. The method of claim 2, wherein diffusing acid from the acidic
marker material into the patterning resist comprises diffusing acid
from the acidic marker material into the segment of the at least
one region of exposed resist to increase the acidity of the segment
of the at least one region of exposed resist.
4. The method of claim 3, further comprising developing the
patterning resist with a positive tone developer to remove at least
the segment of the at least one region of exposed resist.
5. The method of claim 3, further comprising developing the
patterning resist with a negative tone developer to remove the at
least one region of unexposed resist without removing the segment
of the at least one region of exposed resist.
6. The method of claim 2, wherein diffusing acid from the acidic
marker material into the patterning resist comprises diffusing acid
from the acidic marker material into the segment of the at least
one region of unexposed resist to increase the acidity of the
segment of the at least one region of unexposed resist.
7. The method of claim 6, further comprising developing the
patterning resist with a positive tone developer to remove at least
the segment of the at least one region of unexposed resist.
8. The method of claim 6, further comprising developing the
patterning resist with a negative tone developer to remove a
portion of the at least one region of unexposed resist without
removing all the segment of the at least one region of unexposed
resist.
9. The method of claim 1, wherein: forming a patterning resist
above a marker material comprises forming a patterning resist above
a basic marker material; and diffusing a compound from the marker
material into the patterning resist comprises diffusing base from
the basic marker material into the patterning resist to decrease
one of the acidity of the segment of the at least one region of
exposed resist and the acidity of the segment of the at least one
region of unexposed resist.
10. The method of claim 9, wherein diffusing base from the basic
marker material into the patterning resist comprises diffusing base
from the basic marker material into the segment of the at least one
region of unexposed resist to decrease the acidity of the segment
of the at least one region of unexposed resist.
11. The method of claim 10, further comprising developing the
patterning resist with a positive tone developer to remove the at
least one region of exposed resist without removing the segment of
the at least one region of unexposed resist.
12. The method of claim 10, further comprising developing the
patterning resist with a negative tone developer to remove at least
the segment of the at least one region of unexposed resist.
13. The method of claim 9, wherein diffusing base from the basic
marker material into the patterning resist comprises diffusing base
from the basic marker material into the segment of the at least one
region of exposed resist to decrease the acidity of the segment of
the at least one region of exposed resist.
14. The method of claim 13, further comprising developing the
patterning resist with a positive tone developer to remove the at
least one region of unexposed resist without removing the segment
of the at least one region of exposed resist.
15. The method of claim 13, further comprising developing the
patterning resist with a negative tone developer to remove at least
the segment of the at least one region of exposed resist.
16. A method of forming a resist feature, the method comprising:
forming a patterning resist over a base material; and adding acid
or base to a lower area of the patterning resist to alter
developability of the patterning resist in at least a segment of
the patterning resist proximate to the lower area.
17. The method of claim 16, wherein forming a patterning resist
over a base material comprises: forming a discrete feature of a
marker material supported by the base material; and forming the
patterning resist over the base material and the marker
material.
18. The method of claim 17, further comprising: prior to adding
acid or base to a lower area of the patterning resist, selectively
exposing the patterning resist to define at least one region of
exposed resist and at least one region of unexposed resist; and
wherein adding acid or base to a lower area of the patterning
resist comprises: exposing the marker material to energy to
generate the acid or base; and diffusing the acid or base from the
marker material to the lower area of the patterning resist to alter
the developability of the patterning resist in at least a region
proximate to the lower area.
19. A method of forming a pattern in a resist, the method
comprising: forming a resist on a base material; selectively
exposing an upper surface of the resist to define an acidic resist
region and a non-acidic resist region; adding acid to a lower
surface of a segment of the non-acidic resist region to convert the
segment of the non-acidic resist region into an acidic resist
segment, leaving another segment of the non-acidic resist region;
and developing the resist with a developer selective for one of the
acidic resist segment and the another segment of the non-acidic
resist region over another of the acidic resist segment and the
another segment of the non-acidic resist region.
20. The method of claim 19, wherein forming a resist on a base
material comprises: forming a recess in the base material; forming
a marker material in the recess, the marker material comprising a
photo-acidic generator; and forming a patterning resist on the base
material and the marker material
21. The method of claim 19, wherein forming a resist on a base
material comprises: forming a recess in the base material; forming
a marker material in the recess, the marker material comprising a
thermal acidic generator; and forming a patterning resist on the
base material and the marker material.
22. A method of forming a pattern in a resist, the method
comprising: forming a resist on a base material; selectively
exposing an upper surface of the resist to define an acidic resist
region and a non-acidic resist region; adding base to a lower
surface of a segment of the acidic resist region to convert the
segment of the acidic resist region into a non-acidic resist
segment, leaving another segment of the acidic resist region; and
developing the resist with a developer selective for one of the
non-acidic resist segment and the another segment of the acidic
resist region over another of the non-acidic resist segment and the
another segment of the acidic resist region.
23. The method of claim 22, wherein forming a resist on a base
material comprises: forming a recess in the base material; forming
a marker material in the recess, the marker material comprising a
thermal base generator; and forming a patterning resist on the base
material and the marker material.
24. A method of forming an array of aligned elongate resist
features, the method comprising: forming a discrete feature of a
marker material supported by a base material; forming a patterning
resist over the base material; transferring at least one of an acid
and a base from the marker material to a region of the patterning
resist proximate to the discrete feature of the marker material to
increase or decrease developability of the region of the patterning
resist relative to another region of the patterning resist; and
selectively exposing and developing the patterning resist to define
an array of elongate resist features, a plurality of the elongate
resist features of the array terminating in substantial alignment
proximate to the discrete feature of the marker material.
25. The method of claim 25, wherein forming a patterning resist
over the base material comprises applying over the base material
and the marker material a patterning resist dissolved in a solvent
in which the marker material is insoluble.
26. A method of forming a pattern in a resist, the method
comprising: selectively exposing a resist to form at least one
soluble region of the resist, the at least one soluble region of
the resist being soluble in a developer; without exposing the
resist again, transferring to a lower area of a segment of the
resist a compound to alter solubility of the segment of the resist
in the developer; and exposing the resist to the developer.
Description
FIELD
[0001] The present disclosure, in various embodiments, relates
generally to semiconductor device design and fabrication. More
particularly, this disclosure relates to semiconductor fabrication
methods involving techniques for patterning of resist materials for
use in lithography processes.
BACKGROUND
[0002] Photolithographic patterning is a well-established
technology in the manufacturing processes of various integrated
circuits (ICs), including ICs with semiconductor devices and liquid
crystal display panels.
[0003] In photolithography, a mask is used to selectively expose
segments of a resist material to an appropriate energy source or
chemical composition to define a pattern in the resist material.
The resist material may be converted from a non-acidic or basic
resist material to an acidic resist material where exposed. That
is, exposure of the basic resist material activates a photo-acid
generator (PAG) or a thermal acid generator (TAG) within the resist
material to generate acid, making the exposed regions acidic.
Either the regions of exposed, i.e., acidic resist material, or the
regions of unexposed, i.e., basic resist material, may be removed
by a developer in which one of the regions is soluble. In a
positive tone development process, the developer is formulated and
selected such that the exposed, acidic resist regions are soluble
in the developer. A resulting resist feature will, therefore, be
formed from the unexposed, basic resist regions after the exposed,
acidic resist regions are removed in development. In a negative
tone development process, the developer is formulated and selected
such that the unexposed, basic resist regions are soluble in the
developer. A resulting resist feature will, therefore, be formed
from the exposed, acidic resist regions after the unexposed, basic
resist regions are removed in development.
[0004] Chemical interactions between the acidic, exposed resist
regions and the basic, unexposed resist regions may shift an
acid-base equilibrium boundary during or after selective exposure
of the resist. Therefore, an effective "boundary" between the
acidic, exposed resist regions and the basic, unexposed resist
regions may not correspond to the intended boundaries defined by
the mask used during selective exposure. Thus, use of a mask with a
precise, intricate pattern, may not necessarily result in the same
precise, intricate pattern being transferred to the resist. In
addition to the acid-base equilibrium shift, shadowing effects,
topographical and masking complexities, and other limitations of
conventional masking, exposure, and development acts, may further
result in the formed resist pattern not matching the precision or
intricacy of the pattern defined in the mask and may otherwise not
meet tolerances as to the precise pattern needed.
[0005] Areas of the pattern intended to be void of resist material
may be undesirably occupied by resist material due to line merge
issues. Similarly, areas of the pattern intended to be occupied by
resist material may be undesirably unoccupied by resist material
due to line breakage or line collapse issues. For example, when
patterning to form a resist feature that is ideally uniform in
width and height, such as the resist feature 100 illustrated in
FIG. 1, limitations of conventional masking, exposure, and
development acts may produce an undesirably disjoined or "broken,"
resist feature, such as separated resist features 200 illustrated
in FIG. 2. As another example, when patterning to form separated
resist features, e.g., separated resist feature 200 of FIG. 2,
limitations of conventional masking, exposure, and development acts
may produce an undesirably joined resist feature, e.g., resist
feature 100 of FIG. 1. Thus, line breaks may be formed or,
conversely, line merges may be formed where not wanted. As another
example, terminating ends of an array of elongate features formed
in the resist material may not actually terminate in alignment with
one another; some ends may be longer than desired and some ends may
be shorter than desired. Such patterning errors may thereafter be
transferred to underlying materials during subsequent pattern
transfer.
[0006] Efforts have been made to account for shadowing effects and
other limitations of photolithography processes. Such efforts
include optical proximity correction (OPC) methods and phase shift
mask (PSM) methods. With OPC, modifications are made to the pattern
in the mask to compensate for the patterning errors and enable the
desired pattern to be formed in the resist material. Nonetheless,
achieving and transferring a precise, intricate pattern in
patterning materials remains a challenge with conventional
techniques.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an isometric schematic illustration of an
uninterrupted resist feature, intended to be formed according to a
theoretical patterning process for forming an uninterrupted resist
feature or formed according to a conventional patterning process
for forming an interrupted resist feature.
[0008] FIG. 2 is an isometric schematic illustration of an
interrupted resist feature according to an idealized patterning
process for forming an interrupted resist feature or according to a
conventional patterning process for forming an uninterrupted resist
feature.
[0009] FIGS. 3 through 8B are isometric schematic illustrations of
an uninterrupted resist feature during various stages of processing
according to an embodiment of the present disclosure using an
uninterrupted mask, a positive tone development, and basic chemical
proximity correction to a segment of unexposed patterning resist,
wherein FIGS. 5B, 6B, 7B, and 8B are cut-away illustrations of
FIGS. 5A, 6A, 7A, and 8A, respectively.
[0010] FIGS. 9 through 14B are isometric schematic illustrations of
an uninterrupted resist feature during various stages of processing
according to an embodiment of the present disclosure using an
uninterrupted mask, a negative tone development, and acidic
chemical proximity correction to a segment of exposed patterning
resist, wherein FIGS. 11B, 12B, 13B, and 14B are cut-away
illustrations of FIGS. 11A, 12A, 13A, and 14A, respectively.
[0011] FIGS. 15 through 20B are isometric schematic illustrations
of an interrupted resist feature during various stages of
processing according to an embodiment of the present disclosure
using an interrupted mask, a positive tone development, and acidic
chemical proximity correction to a segment of exposed patterning
resist, wherein FIGS. 17B, 18B, 19B, and 20B are cut-away
illustrations of FIGS. 17A, 18A, 19A, and 20A, respectively.
[0012] FIGS. 21 through 26B are isometric schematic illustrations
of an interrupted resist feature during various stages of
processing according to an embodiment of the present disclosure
using an interrupted mask, a negative tone development, and basic
chemical proximity correction to a segment of unexposed patterning
resist, wherein FIGS. 23B, 24B, 25B, and 26B are cut-away
illustrations of FIGS. 23A, 24A, 25A, and 26A, respectively.
[0013] FIG. 27 is an isometric schematic illustration of an array
of aligned elongate resist features intended to be formed according
to an idealized patterning process.
[0014] FIG. 28 is an isometric schematic illustration of an array
of overlength elongate resist features formed according to a
conventional resist patterning process.
[0015] FIG. 29 is an isometric schematic illustration of an array
of underlength elongate resist features formed according to a
conventional resist patterning process.
[0016] FIGS. 30 through 33 are isometric schematic illustrations of
an array of aligned elongate resist features during various stages
of processing according to an embodiment of the present disclosure
using a positive tone development and basic chemical proximity
correction to segments of unexposed patterning resist.
[0017] FIGS. 34 through 37 are isometric schematic illustrations of
an array of aligned elongate resist features during various stages
of processing according to an embodiment of the present disclosure
using a negative tone development and acidic chemical proximity
correction to segments of exposed patterning resist.
[0018] FIGS. 38 through 41 are isometric schematic illustrations of
an array of aligned elongate resist features during various stages
of processing according to an embodiment of the present disclosure
using a positive tone development and acidic chemical proximity
correction to segments of exposed patterning resist.
[0019] FIGS. 42 through 45 are isometric schematic illustrations of
an array of aligned elongate resist features during various stages
of processing according to an embodiment of the present disclosure
using a negative tone development and basic chemical proximity
correction to segments of unexposed patterning resist.
[0020] FIGS. 46 through 50 are isometric schematic illustrations of
an interrupted resist feature during various stages of processing
according to an embodiment of the present disclosure using an
uninterrupted mask, a positive tone development, and acidic
chemical proximity correction to a segment of unexposed patterning
resist, wherein FIGS. 47 through 50 are cut-away illustrations.
[0021] FIG. 51 is an isometric cut-away schematic illustration of
an interrupted resist feature formed according to an embodiment of
the present disclosure using an uninterrupted mask, a negative tone
development, and basic chemical proximity correction to a segment
of unexposed patterning resist.
[0022] FIG. 52 is an isometric cut-away schematic illustration of
an uninterrupted resist feature formed according to an embodiment
of the present disclosure using an interrupted mask, a positive
tone development, and basic chemical proximity correction to a
segment of exposed patterning resist.
[0023] FIG. 53 is an isometric cut-away schematic illustration of
an uninterrupted resist feature formed according to an embodiment
of the present disclosure using an interrupted mask, a negative
tone development, and acidic chemical proximity correction to a
segment of exposed patterning resist.
DETAILED DESCRIPTION
[0024] Methods of forming resist features, of forming a pattern in
a resist, and of forming an array of aligned, elongate resist
features are disclosed. The methods include an addition of a
compound, e.g., an acid or a base, to at least a lower surface of a
patterning resist to alter a level of acidity of at least a segment
of one of an exposed, acidic resist region and an unexposed, basic
resist region. The alteration, e.g., increase or decrease, in the
level of acidity in the resist segment shifts the acid-base
equilibrium in the segment so as to either encourage or discourage
development of the segment by a developer. Accordingly, where a
resist pattern may be otherwise vulnerable to undesired line
breakage during development, chemical correction to the patterning
resist may be made at the vulnerable region to discourage
development of the patterning resist at the vulnerable region.
Alternatively, where a resist pattern may be otherwise vulnerable
to undesired line merge during development, chemical correction to
the patterning resist may be made at the vulnerable region to
encourage development of the patterning resist at the vulnerable
region. This technique, which may be characterized as "chemical
proximity correction," may be used instead of, or in combination
with, OPC to compensate for vulnerabilities, errors, or defects in
photolithography processes for patterning a resist material.
[0025] The chemical correction may include transfer of an acid or
base from a marker material over which the patterning resist is
formed. The marker material, which may be supported by a base
material, may be formulated as an acidic or acid-generating marker
material or as a basic or base-generating marker material. Acid
from an acidic or acid-generating marker material may therefore
diffuse into a segment of the patterning resist to increase the
acidity of the segment, enabling the segment to be more likely to
be developed by a positive tone developer and less likely to be
developed by a negative tone developer. Conversely, base from a
basic or base-generating marker material may diffuse into a segment
of the patterning resist to decrease the acidity of the segment,
enabling the segment to be less likely to be developed by a
positive tone developer and more likely to be developed by a
negative tone developer. In some embodiments, the marker material
may be formulated to include or generate sufficient acid to
chemically convert a segment of basic, unexposed patterning resist
to a segment of acidic resist such that the segment will be
effectively developable or nondevelopable along with the acidic,
exposed resist regions. Conversely, in some embodiments, the marker
material may be formulated to include or generate sufficient base
to chemically convert a segment of acidic, exposed patterning
resist to a segment of basic resist such that the segment will be
effectively developable or nondevelopable along with the basic,
unexposed resist regions.
[0026] Thus, the marker material may be used in some embodiments to
mark specific areas corresponding to vulnerable regions of the
patterning resist, i.e., regions prone to undesirable line break or
undesirable line merge. In other embodiments, the marker material
may be used to mark a boundary with which features formed in the
patterning resist are desired to be aligned. Accordingly, a
patterning resist, the acidity of a portion of which has been
altered after formation of the patterning resist and without
forming another material on or over the patterning resist, may be
used to define a more intricate pattern than that definable by
conventional techniques. The chemical proximity correction
techniques may also be used to pattern a resist with a pattern
purposefully differing from a masked pattern. That is, regions of
the patterning resist exposed in a masked pattern may be chemically
converted to effectively unexposed regions after exposure, and vice
versa.
[0027] As used herein, the term "substrate" means and includes a
base material or construction upon which components, such as those
within memory cells as well as other semiconductor device
structures, are formed. The substrate may be a semiconductor
substrate, a base semiconductor material on a supporting structure,
a metal electrode, or a semiconductor substrate having one or more
materials, structures, or regions formed thereon. The substrate may
be a conventional silicon substrate or other bulk substrate
including a semiconductive material. As used herein, the term "bulk
substrate" means and includes not only silicon wafers, but also
silicon-on-insulator ("SOI") substrates, such as
silicon-on-sapphire ("SOS") substrates or silicon-on-glass ("SOG")
substrates, epitaxial layers of silicon on a base semiconductor
foundation, or other semiconductor or optoelectronic materials,
such as silicon-germanium (Si.sub.1-xGe.sub.x, where x is, for
example, a mole fraction between 0.2 and 0.8), germanium (Ge),
gallium arsenide (GaAs), gallium nitride (GaN), or indium phosphide
(InP), among others. Furthermore, when reference is made to a
"substrate" in the following description, previous process stages
may have been utilized to form materials, regions, or junctions in
or on the base semiconductor structure or foundation.
[0028] As used herein, the term "patterning resist" means and
includes a photoresist material formulated such that the material
may be applied or otherwise formed and processed to remove only
select segments thereof so as to define a pattern therein. The
pattern in the patterning resist may, thereafter, be transferred to
the base material to form a patterned base material exhibiting the
pattern of the patterning resist. For example, and without
limitation, the patterning resist may be a conventional 248 nm
resist or 193 nm resist, such as a methacrylate-based or cyclic
olefin-based photoresist.
[0029] As used herein, the term "developable" means a resist
material formulated to be selectively dissolved or otherwise
removed by an appropriate developer following exposure to an
appropriate energy source or to a chemical composition formulated
to alter miscibility of the developable material with the
developer. Therefore, as used herein, a material referred to as
"developable" may be selectively soluble in an appropriate
developer. Resists formulated to be developable by a positive tone
developer are formulated such that acidic regions of the resist are
developable by the positive tone developer. Resist formulated to be
developable by a negative tone developer are formulated such that
basic regions of the resist are developable by the negative tone
developer. Thus, a positive resist is "developable" in that, due to
exposure to an appropriate wavelength of radiation or to an
appropriate chemical composition, the exposed segments of the
positive resist become acidic and may be removed by an appropriate
positive tone developer in which only the acidic regions of the
positive resist are soluble and in which basic regions of the
positive resist are insoluble. A negative resist is "developable"
in that, unless exposed to appropriate radiation or an appropriate
chemical composition, unexposed regions of the negative resist
material are basic, while exposed regions are acidic, and the basic
regions are soluble or otherwise removable by a negative tone
developer while acidic regions of the negative resist are
insoluble.
[0030] As used herein, the term "marker material" means and
includes a photoresist material or other material formulated to
include or generate acid or base and to transfer at least a portion
of that acid or base to a material in proximity with the marker
material, e.g., an overlying patterning resist material, so as to
alter the acidity of the proximate material. The marker material
may be a conventional 248 nm resist or 193 nm resist, such as a
methacrylate-based or cyclic olefin-based photoresist. The marker
material may alternatively or additionally include a bottom
anti-reflective coating (BARC) material, a top anti-reflective
coating (TARC) material, or other such materials that contain acid
or base such that the marker material is formulated to transfer an
acid or base to a proximate material. The marker material may
alternatively or additionally include one or more of a photo acid
generator (PAG) and a thermal acid generator (TAG), such that the
marker material is formulated as an acid-generating marker
material, which, upon exposure to an appropriate energy source,
will generate acid and transfer at least a portion of the acid to a
proximate material. Conversely, the marker material may
alternatively or additionally include a thermal base generator
(TBG), such that the marker material is formulated as a
base-generating marker material, which, upon exposure to heat, will
generate base and transfer at least a portion of the base to a
proximate material.
[0031] If, for example, a positive tone development process is to
be used, use of an acidic or acid-generating marker material may
encourage development and removal of a proximate segment of
patterning resist while use of a basic or base-generating marker
material may discourage development of the segment. If, as another
example, a negative tone development process is to be used, use of
an acidic or acid-generating marker material may discourage
development of a proximate segment of patterning resist while use
of an acidic or acid-generating marker material may encourage
development and removal of the segment.
[0032] As used herein, the terms "acidic resist," "acidic
patterning resist," "acidic region," "acidic resist region,"
"acidic marker material," and "acid-generating marker material"
mean and include a resist, patterning resist, region, resist
region, and marker material, respectively, having, at least at some
stage during processing, a pH below about 7.0. The acidic resist,
patterning resist, region, resist region, or marker material may be
acidic due to initial formation, due to acid loading before or
after formation, or due to post-formation processing the affects
the acidity of the material, such as exposure to light, heat, or
other energy or appropriate compound or mixture of compounds.
[0033] As used herein, the terms "basic resist," "basic patterning
resist," "basic region," "basic resist region," "basic marker
material," and "base-generating marker material" mean and include a
resist, patterning resist, region, resist region, and marker
material, respectively, having, at least at some stage during
processing, a pH above about 7.0. The basic resist, patterning
resist, region, resist region, or marker material may be basic due
to initial formation, due to base loading before or after
formation, or due to post-formation processing that affects the
basicity of the material, such as exposure to heat, or other energy
or approximate chemical or mixture of chemicals.
[0034] As used herein, the terms "positive tone developer" and
"positive tone development" means and includes a developer and
development process, respectively, in which the developer is
formulated such that acidic regions of resist are soluble in the
developer.
[0035] As used herein, the terms "negative tone developer" and
"negative tone development" mean and include a developer and
development process, respectively, in which the developer is
formulated such that basic regions of resist are soluble in the
developer.
[0036] As used herein, the term "vulnerable region," means and
includes a region of a resist desired to be developed, but prone to
nondevelopment by conventional techniques (i.e., without a chemical
proximity correction according to the present disclosure), and a
region of a resist desired not to be developed, but prone to
development by conventional techniques (i.e., without a chemical
proximity correction according to the present disclosure).
[0037] As used herein, spatially relative terms, such as "beneath,"
"below," "lower," "bottom," "above," "upper," "top," "front,"
"rear," "left," "right," and the like, may be used for ease of
description to describe one element's or feature's relationship to
another element(s) or feature(s) as illustrated in the figures.
Unless otherwise specified, the spatially relative terms are
intended to encompass different orientations of the materials in
addition to the orientation depicted in the figures. For example,
if materials in the figures are inverted, elements described as
"below" or "beneath" or "under" or "on bottom of" other elements or
features would then be oriented "above" or "on top of" the other
elements or features. Thus, the term "below" can encompass both an
orientation of above and below, depending on the context in which
the term is used, which will be evident to one of ordinary skill in
the art. The materials may be otherwise oriented (rotated ninety
degrees, inverted, etc.) and the spatially relative descriptors
used herein interpreted accordingly.
[0038] As used herein, reference to an element as being "on" or
"over" another element means and includes the element being
directly on top of, adjacent to, underneath, or in direct contact
with the other element. It also includes the element being
indirectly on top of, adjacent to, underneath, or near the other
element, with other elements present therebetween. In contrast,
when an element is referred to as being "directly on" another
element, there are no intervening elements present.
[0039] As used herein, the terms "comprises," "comprising,"
"includes," and/or "including" specify the presence of stated
features, structures, regions, integers, stages, operations,
elements, materials, components, and/or groups, but do not preclude
the presence or addition of one or more other features, structures,
regions, integers, stages, operations, elements, materials,
components, and/or groups thereof.
[0040] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0041] As used herein, the singular forms "a," "an," and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise.
[0042] The illustrations presented herein are not meant to be
actual views of any particular material, feature, structure,
region, or segment, but are merely idealized representations that
are employed to describe embodiments of the present disclosure.
[0043] Embodiments are described herein with reference to the
accompanying drawing figures. Variations from the shapes of the
structures depicted in the figures as a result, for example, of
manufacturing techniques and/or tolerances, are to be expected.
Thus, embodiments described herein are not to be construed as being
limited to the particular shapes or regions as illustrated but
include deviations in shapes that result, for example, from
manufacturing. For example, a region illustrated or described as
box shaped may have rough and/or nonlinear structures. Moreover,
sharp angles that are illustrated may be rounded. Thus, the regions
illustrated in the figures are schematic in nature and their shapes
are not intended to illustrate the precise shape of a region and do
not limit the scope of the present claims.
[0044] The following description provides specific details, such as
material types and processing conditions, in order to provide a
thorough description of some embodiments of the disclosed devices
and methods. However, a person of ordinary skill in the art will
understand that the embodiments of the methods may be practiced
without employing these specific details. Indeed, the embodiments
of the methods may be practiced in conjunction with conventional
semiconductor fabrication techniques employed in the industry.
[0045] The fabrication processes described herein do not form a
complete process flow for processing semiconductor device
structures. The remainder of the process flow is known to those of
ordinary skill in the art. Accordingly, only the methods and
structures necessary to understand embodiments of the present
devices and methods are described herein.
[0046] Unless the context indicates otherwise, the materials
described herein may be formed by any suitable technique including,
but not limited to, spin coating, knife coating, dip coating,
blanket coating, chemical vapor deposition ("CVD"), atomic layer
deposition ("ALD"), plasma enhanced ALD, and physical vapor
deposition ("PVD"). Alternatively, the materials may be grown in
situ. Depending on the specific material to be formed, the
technique for depositing or growing the material may be selected by
a person of ordinary skill in the art.
[0047] Unless the context indicates otherwise, the removal of
materials described herein may be accomplished by any suitable
technique including, but not limited to, etching, abrasive
planarization, and other methods.
[0048] Reference will now be made to the drawings, where like
numerals refer to like components throughout. The drawings are not
necessarily drawn to scale.
[0049] Methods of forming resist features, of forming a pattern in
a resist, and of forming an array of elongate resist features are
disclosed. The methods include forming a patterning resist above a
base material. The patterning resist is selectively exposed to form
one or more regions of exposed resist and unexposed resist. A
compound, e.g., an acid or a base, is transferred to a lower
surface of a segment of the patterning resist to alter a level of
acidity of the segment to either encourage or discourage the
development of the segment. The compound may be transferred to the
segment from a marker material over which the patterning material
is formed. Accordingly, the method provides for forming resist
features and resist patterns while avoiding undesirable line
breaks, undesirable line merges, misalignments, and other such
patterning inaccuracies.
[0050] The methods disclosed herein may be used to form
semiconductor device structures. As nonlimiting examples, the
methods may be used to form conductive contacts, conductive
interconnects, transistors, and memory devices, including, for
example, in dynamic random access memory (DRAM) cells, non-volatile
memory cells, and NAND flash memory.
[0051] FIGS. 1 and 2 illustrate resist features 100, 200, which may
be formed over a base material 10. The base material 10 may include
a substrate 12 and one or more other materials, such as a hardmask
14, supported by the substrate 12. The substrate 12 may be a
semiconductor substrate. The hardmask 14 may be silicon or a
metal-containing material, a BARC, a TARC, an acid-rinsed material,
a topcoat material, or one or more of these materials.
[0052] In certain circumstances, the uninterrupted resist feature
100 illustrated in FIG. 1 may be desired. However, limitations of
conventional photolithography processes may produce an interrupted
resist feature, e.g., the interrupted resist feature 200
illustrated in FIG. 2. Thus, resist material 16 at region 18 may be
vulnerable to development and may be developed and removed though
the resist material 16 at region 18 is intended and desired to
remain after formation of the uninterrupted resist feature 100. The
resist material 16 at region 18 may be vulnerable because of
acid-base equilibrium shifts between exposed and non-exposed
regions of the resist, because of shadowing effects, because of
topographical and masking complexities, or other limitations of
conventional masking, exposure, and development acts. Thus,
undesirable "line breakage" may form the interrupted resist feature
200, instead of the uninterrupted resist feature 100.
[0053] In other circumstances, an interrupted resist feature, such
as the interrupted resist feature 200, may be desired. However,
limitations of conventional photolithography processes may produce
an undesirably "line merged" resist feature, such as the
uninterrupted resist feature 100. In such circumstances, region 18
presents a segment of resist material 16 desired to not be
developed, but which is undesirably developed and removed during
development.
[0054] Chemical proximity correction techniques, according to some
embodiments of the present disclosure, may be used to form an
uninterrupted resist feature without line breakage, as illustrated
in FIGS. 3 through 14B, or to form an interrupted resist feature
without line merge, as illustrated in FIGS. 15 through 26B, by
appropriately encouraging or discouraging development of segments
of patterning resist in accordance with masks used for selective
exposure of the patterning resist. Thus, segments left unexposed to
prevent development by a positive tone developer are altered
chemically with base to discourage development, segments exposed to
prevent development by a negative tone developer are altered
chemically with acid to discourage development, segments exposed to
accommodate development by a positive tone developer are altered
chemically with acid to encourage development, and segments
unexposed to accommodate development by a negative tone developer
are altered chemically with base to encourage development.
[0055] FIGS. 3 through 8B illustrate a method of forming an
uninterrupted resist feature using positive tone development and
basic chemical proximity correction on a segment of unexposed
patterning resist. With reference to FIG. 3, a base material 10,
which may include a substrate 12 and one or more other materials,
such as a hardmask 14, is provided. A recess 20 may be formed in
the base material 10, e.g., in the hardmask 14. The recess 20 may
be formed at an area corresponding to a region where the resist
feature to be formed is known to be vulnerable to line breakage,
e.g., at region 18 of FIGS. 1 and 2.
[0056] The recess 20 may be a shallow recess, i.e., a recess that
extends partially into the thickness of the hardmask 14. The recess
20 may define a low aspect ratio (i.e., a ratio of the height of
the recess 20 to the width of the recess 20 that is less than 1:1,
e.g., 1:2 or 1:4). The recess 20 may be formed by conventional
methods, which are not described in detail herein.
[0057] As illustrated in FIG. 4, a marker material 30 may be formed
in the recess 20 by conventional methods. The marker material 30
may be formed in the recess 20 at a thickness of from approximately
5 nm to approximately 20 nm. After exposing the marker material 30
to heat (i.e., a soft bake), the marker material 30 and the
hardmask 14 may be planarized by an appropriate conventional
method, e.g. chemical-mechanical planarization (CMP), so that a
primary, exposed surface of the marker material 30 is co-planar
with a primary surface of the hardmask 14. In other embodiments
(not shown), the marker material 30 may extend above the primary
surface of the hardmask 14.
[0058] The marker material 30 may be a basic marker material 31.
For example, and without limitation, the basic marker material 31
may be a resist material including a thermal base generator (TBG),
e.g., between about 0.01 weight percent and about 10 weight percent
TBG. Upon heating the TBG-including basic marker material 31, base
may be generated in the marker material 31. Such TBG-containing
basic marker material 31 may be formed over the hardmask 14, e.g.,
in the recess 20 formed in the hardmask 14, then heated to generate
base within the basic marker material 31. Alternatively, the basic
marker material 31 may become basic by adding base to the marker
material 30 during or after formation in the recess 20.
[0059] With reference to FIGS. 5A and 5B, a patterning resist 40 is
formed over the base material 10 and the basic marker material 31.
The patterning resist 40 may be formed after the marker material 30
is made basic or before the marker material 30 is made basic. For
example, a TBG-including marker material 30 may be heated after the
patterning resist 40 is formed to activate the TBG and generate
base, resulting in the patterning resist 40 overlying the basic
marker material 31.
[0060] The patterning resist 40, upon initial formation may be a
basic patterning resist 41, which is otherwise referred to herein
as a "non-acidic" resist. Forming the patterning resist 40 over the
marker material 30 may be accomplished using an appropriate
conventional formation method, such as spin coating of the
patterning resist 40 material. In some embodiments, both the marker
material 30 and the patterning resist 40 are resist materials.
Therefore, each of the marker material 30 and the patterning resist
40 may be formed using a solution of the marker material 30 and a
solution of the patterning resist 40, respectively. The solvent
used to form the marker material 30 solution and the patterning
resist 40 solution may be selected dependent on the miscibility and
immiscibility of the other resist material. For example, the
solvent may be an alcohol, cyclohexanone, propylene glycol methyl
ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), or
combinations thereof. Since the patterning resist 40 may be formed
over the marker material 30, the solvent in which the patterning
resist 40 is dissolved during application of the patterning resist
40 may be formulated to be immiscible with the marker material 30.
Accordingly, forming the patterning resist 40 may not affect the
as-formed marker material 30.
[0061] For example, without limitation, the marker material 30 may
be dissolved in an organic solvent, and the solution of the marker
material 30 in the organic solvent may be formed in or over the
hardmask 14. Once formed, the marker material 30 may be exposed to
radiation or heat to convert the marker material 30 to a material
immiscible in the organic solvent. Thereafter, the patterning
resist 40, which may include the same resist material used as the
marker material 30, may be formed over the marker material 30 using
the same organic solvent. The exposed marker material 30, now being
immiscible in the organic solvent, may not be affected by the
formation of the patterning resist 40 using the solution of the
patterning resist 40 in the organic solvent.
[0062] With reference to FIGS. 6A and 6B, the patterning resist 40
may be selectively exposed to an appropriate energy source, e.g.,
light or radiation, or to a chemical composition to alter the
miscibility of the exposed regions of the patterning resist 40 in a
developer to be used relative to the miscibility of the unexposed
regions of the patterning resist 40. A mask 50 may be used to
selectively conceal from exposure the regions to remain unexposed.
The mask 50 may conceal an uninterrupted region of the basic
patterning resist 41, as illustrated in FIG. 6A.
[0063] With reference to FIGS. 7A and 7B, the selective exposure of
the patterning resist 40 defines at least one region of exposed
resist and at least one region of unexposed resist. Because
exposure converts the patterning resist 40 from the original, basic
patterning resist 41 to an acidic patterning resist 42, the
selective exposure defines at least one region of acidic patterning
resist 42 and at least one region of basic patterning resist 41.
The region of basic patterning resist 41 may at least partially
conform to a pattern defined by the mask 50 used.
[0064] As illustrated in FIG. 7B, base from the basic marker
material 31 may diffuse into a lower area of a segment of the
patterning resist 40 proximate to the basic marker material 31. The
base may diffuse in the direction illustrated by arrows 60.
Therefore, the basic marker material 31 increases the basicity, and
therefore decreases the acidity, of the segment of the patterning
resist 40 proximate, e.g., overlying, the basic marker material 31.
The base transferred to the segment of the patterning resist 40
from the basic marker material 31 may therefore alter the acidity
of a segment of the patterning resist 40, altering the miscibility
of the segment of the patterning resist 40 in a developer to be
used during development.
[0065] During development, therefore, as illustrated in FIGS. 8A
and 8B, a positive tone developer, selective for the regions of
exposed, acidic patterning resist 42 and in which the acidic
patterning resist 42 is miscible, is used to develop and remove the
acidic patterning resist 42, leaving the basic patterning resist
41, including the segment of patterning resist 40 proximate to the
basic marker material 31. Accordingly, an uninterrupted resist
feature 800 is formed.
[0066] Because the basic marker material 31 transferred base to a
proximate segment of the patterning resist 40 to discourage
development, the patterning resist 40 directly overlying and
disposed nearby the basic marker material 31 may not be removed
during development, preventing unwanted line breakage. The
dimensions of the affected segment of the patterning resist 40
affected by the base transferred from the basic marker material 31
may depend on the basicity of the basic marker material 31 and
other conditions of the materials during processing. It is
contemplated that the amount of base in the basic marker material
31 and the conditions for processing may be tailored to achieve an
affected segment of desired dimensions. For example, the basic
marker material 31 may be formulated to have a higher amount of
base if a relatively-large segment of patterning resist 40 is to be
affected compared to a basic marker material 31 formulated to
affect a relatively-small segment of patterning resist 40.
[0067] FIGS. 9 through 14B illustrate a method of forming an
uninterrupted resist feature using negative tone development and
acidic chemical proximity correction on a segment of exposed
patterning resist. With reference to FIGS. 9 and 10, the recess 20
may be formed in the base material 10, and the marker material 30
formed in the recess 20 by conventional methods. The marker
material 30 may be an acidic marker material 32. The acidic marker
material 32 may be a resist material including an acid-generating
material, such as a thermal-acid-generator (TAG), a
photo-acid-generator (PAG), or both. More specifically, the acidic
marker material 32 may be a resist material including between about
0.01 weight percent and about 10 weight percent PAG. Upon heating
or photo-exposing the TAG-containing acidic marker material 32 or
the PAG-containing acidic marker material 32, respectively, acid
may be generated in the acidic marker material 32. Such
TAG-containing or PAG-containing acidic marker material 32 may be
formed over the hardmask 14, e.g., in the recess 20 formed in the
hardmask 14, then heated or photo exposed to generate acid within
the acidic marker material 32 before the patterning resist 40 is
formed over the acidic marker material 32. In other embodiments,
the acidic marker material 32 may be acid loaded before or after
forming the marker material 30 so as to form the acidic marker
material 32. The acidic patterning resist 42 may be acidic due to
its initial formulation, due to acid loading after formation, or
due to post-formation processing, e.g., exposure to light or other
radiation.
[0068] With reference to FIGS. 11A and 11B, the patterning resist
40 may be formed over the base material 10 and the acidic marker
material 32. The patterning resist 40 may be formed after the
marker material 30 becomes acidic or before the marker material
becomes acidic. For example, a TAG-containing or PAG-containing
marker material 30 may be heated or exposed to light after the
patterning resist 40 is formed to activate the TAG or PAG and
generate acid, resulting in the patterning resist 40 overlying the
acidic marker material 32.
[0069] With reference to FIGS. 12A and 12B, the patterning resist
40, which may initially be a basic patterning resist 41, may be
selectively exposed using a mask 50 defining an uninterruptible
feature pattern overlying the acidic marker material 32. With
reference to FIGS. 13A and 13B, the selective exposure defines
regions of unexposed, basic patterning resist 41 and at least one
region of exposed, acidic patterning resist 42. Acid from the
acidic marker material 32 may diffuse in the direction of arrows 60
to increase the acidity of the patterning resist 40 in a segment
proximate to the acidic marker material 32, altering the
miscibility of the segment of the patterning resist 40 in a
developer to be used during development.
[0070] The patterning resist may be subsequently developed, as
illustrated in FIGS. 14A and 14B, using a negative tone developer,
selective for the regions of unexposed, basic patterning resist 41
and in which the segment of acid-enhanced patterning material
proximate to the acidic marker material 32 is immiscible.
Accordingly, an uninterrupted resist feature 1400 is formed.
[0071] Because the acidic marker material 32 transferred acid to a
proximate segment of the patterning resist 40 to prevent
development, the patterning resist 40 directly overlying the acidic
marker material 32 and portions of the patterning resist 40 nearby
may not be removed during development, discouraging unwanted line
breakage. The dimensions of the affected segment of the patterning
resist 40 affected by the acid transferred from the acidic marker
material 32 may depend on the acidity of the acidic marker material
32 and other conditions of the materials during processing. It is
contemplated that the amount of acid in the acidic marker material
32 and the conditions for processing may be tailored to achieve an
affected segment of desired dimensions. For example, the acid
marker material 32 may be formulated to have a higher level of acid
if a relatively-large segment of patterning resist 40 is to be
affected compared to an acidic marker material 32 formulated to
affect a relatively-small segment of patterning resist 40.
[0072] FIGS. 15 through 20B illustrate a method of forming an
interrupted resist feature using positive tone development and
acidic chemical proximity correction to a segment of exposed
patterning resist. With reference to FIGS. 15 and 16, an acidic
marker material 32 may be formed in a recess 20. With reference to
FIGS. 17A and 17B, a patterning resist 40 that is initially a basic
patterning resist 41 may be formed over the acidic marker material
32 and the base material 10. With reference to FIGS. 18A and 18B,
the patterning resist 40 may be selectively exposed using a mask 50
that is interrupted, which interruption may be disposed over the
acidic marker material 32. A region of acidic patterning resist 42
and regions of basic patterning resist 41 may therefore be defined,
as illustrated in FIGS. 19A and 19B.
[0073] With reference to FIG. 19B, acid from the acidic marker
material 32 may be transferred to a lower area of the patterning
resist 40 in the direction of arrows 60 to increase the acidity of
the segment of patterning resist 40 proximate to the acidic marker
material 32, i.e., a segment of the exposed, acidic patterning
resist 42. As illustrated in FIGS. 20A and 20B, a positive tone
developer, in which the acidic patterning resist 42, including the
segment of acid-enhanced patterning resist 40, is soluble and in
which the basic patterning resist 41 is not soluble, may be used to
develop and remove the acidic patterning resist 42 and
acid-enhanced segment of patterning resist 40 to form an
interrupted resist feature 2000.
[0074] Because the acidic marker material 32 transferred acid to a
proximate segment of the patterning resist 40 to encourage
development, the patterning resist 40 directly overlying the acidic
marker material 32 and portions of the patterning resist 40 nearby
may be removed during development, discouraging unwanted line
merge. It is contemplated that the amount of acid in the acidic
marker material 32 and the conditions for processing may be
tailored to achieve an affected segment of desired dimensions.
Notably, though FIGS. 20A and 20B illustrate edges of the resulting
interrupted resist feature 2000 intersecting with edges of the
acidic marker material 32, the resulting interrupted resist feature
2000 may, in other embodiments, include edges that overly or are
disposed more distal from the edges of the acidic marker material
32 than that illustrated in FIGS. 20A and 20B.
[0075] FIGS. 21 through 26B illustrate a method of forming an
interrupted resist feature using negative tone development and
basic chemical proximity correction on a segment of unexposed
patterning resist. With reference to FIGS. 21 and 22, a basic
marker material 31 may be formed in a recess 20. With reference to
FIGS. 23A and 23B, a patterning resist 40 of basic patterning
resist 41 may be formed over the basic marker material 31. As
illustrated in FIGS. 24A and 24B, the patterning resist 40 may be
selectively exposed using a mask 50 that is interrupted, which
interruption may be disposed over the basic marker material 31.
Regions of acidic patterning resist 42 and a region of basic
patterning resist 41 are therefore defined, as illustrated in FIGS.
25A and 25B.
[0076] With reference still to FIG. 25B, base from the basic marker
material 31 may diffuse into the patterning resist 40 in the
direction of arrows 60 to increase the basicity of, i.e., decrease
the acidity of, the segment of patterning resist 40 proximate to
the basic marker material 31, i.e., the segment of basic patterning
resist 41 overlying the basic marker material 31. The miscibility
of the segment of base-enhanced patterning resist 40 may therefore
be altered. As illustrated in FIGS. 26A and 26B, a negative tone
developer may thereafter be used to develop the patterning resist
40 to remove the region of basic patterning material 41, including
the segment of patterning resist 40 proximate to the basic marker
material 31, forming an interrupted resist feature 2600.
[0077] Because the basic marker material 31 transferred base to a
proximate segment of the patterning resist 40 to encourage
development, the patterning resist 40 directly overlying the basic
marker material 31 and portions of the patterning resist 40 nearby
may be removed during development, discouraging unwanted line
merge. It is contemplated that the amount of base in the basic
marker material 31 and the conditions for processing may be
tailored to achieve an affected segment of desired dimensions and
that the edges of the resulting interrupted resist feature 2600 may
overlap, intersect, or not contact the edges of the basic marker
material 31.
[0078] Accordingly, disclosed is a method of forming a resist
feature, the method comprising forming a patterning resist above a
marker material supported by a base material. The patterning resist
is selectively exposed to define at least one region of exposed
resist and at least one region of unexposed resist. An acidity of
the at least one region of exposed resist exceeds an acidity of the
at least one region of unexposed resist. A compound is diffused
from the marker material into the patterning resist to alter at
least one of the acidity of a segment of the at least one region of
exposed resist and the acidity of a segment of the at least one
region of unexposed resist.
[0079] Also disclosed is a method of forming a resist feature, the
method comprising forming a patterning resist over a base material.
Acid or base is added to a lower area of the patterning resist to
alter developability of the patterning resist in at least a region
proximate to the lower area.
[0080] A method of forming an array of aligned elongate resist
features is also disclosed. FIG. 27 illustrates an array of aligned
elongate resist features 2700 in which elongate resist features 17
each terminate in alignment with one another along a border 19.
While the uniform alignment exhibited by the array of aligned
elongate resist features 2700 is desired, limitations of
conventional photolithography processes may produce an array of
elongate resist features that are not aligned with one another and
the border 19, such as an array of overlength elongate resist
features 2800 illustrated in FIG. 28 or such as an array of
underlength elongate resist features 2900 illustrated in FIG. 29.
Chemical proximity correction techniques according to the present
disclosure may be used to achieve a more uniform alignment of the
features.
[0081] FIGS. 30 through 33 illustrate a method of forming an array
of aligned elongate resist features using positive tone development
and basic chemical proximity correction to segments of unexposed
patterning resist. With reference to FIG. 30, a trench 21 may be
formed in the base material 10, e.g., in the hardmask 14. The
trench 21 may be formed along an area corresponding to a portion of
the base material 10 at which the elongate resist features to be
formed are desired to be in alignment, e.g., at border 19 of FIGS.
27 through 29. The trench 21 may be a shallow trench of depth and
dimensions similar to those of the recess 20 (e.g., FIG. 3)
described above.
[0082] A marker material 30, which may be formulated as a basic
marker material 31, may be formed in the trench 21. As illustrated
in FIG. 31, a patterning material 40 may be formed thereover and
masked using a mask 50 defining regions of the patterning material
40 to be exposed and, accordingly, regions of the patterning
material 40 to remain as unexposed, basic patterning resist 41.
With reference to FIG. 32, the selective exposure forms at least
one region of exposed, acidic patterning resist 42 surrounding
defined regions, corresponding to the desired features of the
elongate resist features to be formed, of basic patterning resist
41. As discussed above with regard to FIG. 7B, base may diffuse
from the basic marker material 31 into proximate segments of the
patterning material 40, e.g., the patterning material 40 overlying
and disposed near to the basic marker material 31. This base
diffusion may enhance the basicity of segments of basic patterning
resist 41 overlying the basic marker material 31. However, the
marker material 30 may be formulated such that base diffused from
the basic marker material 31 into proximate segments of the acidic
patterning resist 42 may not be sufficient to effectively convert
the segments of the acidic patterning resist 42 into basic
patterning resist 41, i.e., less base may be transferred from the
basic marker material 31 into the proximate segments of acidic
patterning resist 42 than would be necessary to increase the pH in
the proximate segments of acidic patterning resist 42 to a point in
which the solubility of the proximate segments in a developer to be
used is changed between soluble and insoluble. Therefore, the
transfer of base from the basic marker material 31 to proximate
segments of the patterning resist 40 may discourage unwanted
development of the segments of the basic patterning resist 41
regions proximate to the basic marker material 31 without
effectively preventing development of the segments of the acidic
patterning resist 42 region proximate to the basic marker material
31.
[0083] As illustrated in FIG. 33, following development with a
positive tone developer, selective for the acidic patterning resist
42, an array of aligned, elongate resist features 3300 is formed
from the remaining basic patterning resist 41, including the
base-enhanced segments of the basic patterning resist 41 proximate
to the basic marker material 31. Because the basic marker material
31 transferred base to proximate segments of the patterning resist
40 to discourage development of proximate segments of basic
patterning resist 41 without effectively inhibiting development of
proximate segments of acidic patterning resist 42, segments of
basic patterning resist 41 directly overlying and disposed near the
basic marker material 31 may not be removed during development,
discouraging unwanted underlength elongate features, such as those
illustrated in FIG. 29. Rather, each of the elongate resist
features of the array 3300 may terminate proximate to the border 19
marked by the basic marker material 31. For example, the elongate
resist features of the array 3300 may each terminate near a distal
edge of the basic marker material 31.
[0084] FIGS. 34 through 37 illustrate a method of forming an array
of aligned elongate resist features using negative tone development
and acidic chemical proximity correction to segments of exposed
patterning resist. With reference to FIG. 34, an acidic marker
material 32 may be formed in trenches 21 defined in the base
material 10. With reference to FIG. 35, a patterning resist 40 may
be formed thereover and selectively exposed using a mask 50. As
illustrated in FIG. 36, the selective exposure forms regions of
acidic patterning resist 42 and a region of basic patterning resist
41. As discussed above with regard to FIG. 13B, acid may diffuse
from the acidic marker material 32 into proximate segments of the
patterning material 40, e.g., the patterning material 40 overlying
and disposed near to the acidic marker material 32. This acid
diffusion may enhance the acidity of the segments of acidic
patterning resist 42 overlying the acidic marker material 32.
However, the marker material 30 may be formulated such that acid
diffused from the acidic marker material 32 into proximate segments
of basic patterning resist 41 may not be sufficient to effectively
convert the proximate segments of basic patterning resist 41 into
acidic patterning resist 42, i.e., less acid may be transferred
from the acid marker material 32 into the proximate segments of
basic patterning resist 41 than would be necessary to decrease the
pH in the proximate segments of basic patterning resist 41 to a
point in which the solubility of the proximate segments in a
developer to be used is changed between soluble and insoluble.
Therefore, the transfer of acid from the acidic marker material 32
to proximate segments of the patterning resist 40 may discourage
unwanted development of the segments of the acidic patterning
resist 42 regions proximate to the acidic marker material 32
without effectively preventing development of the segments of the
basic patterning resist 41 region proximate to the acidic marker
material 32.
[0085] As illustrated in FIG. 37, following development with a
negative tone developer, selective for the basic patterning resist
41, an array of aligned, elongate resist features 3700 is formed
from the remaining acidic patterning resist 42, including the
acid-enhanced segments of the acidic patterning resist 42 proximate
to the acidic marker material 32. Because the acidic marker
material 32 transferred acid to proximate segments of the
patterning resist 40 to discourage development of proximate
segments of acidic patterning resist 42 without effectively
inhibiting development of proximate segments of basic patterning
resist 41, segments of acidic patterning resist 42 directly
overlying and disposed near the acidic marker material 32 may not
be removed during development, discouraging unwanted underlength
elongate features, such as those illustrated in FIG. 29. Rather,
each of the elongate features of the array 3700 may terminate
proximate to the border 19 marked by the acidic marker material 32.
For example, the elongate resist features of the array 3700 may
each terminate near a distal edge of the acidic marker material
32.
[0086] FIGS. 38 through 41 illustrate a method of forming an array
of aligned elongate resist features using positive tone development
and acidic chemical proximity correction to segments of exposed
patterning resist. With reference to FIG. 38, an acidic marker
material 32 may be formed in a trench 21 defined in the base
material 10. With reference to FIG. 39, a patterning resist 40 may
be formed thereover and selectively exposed using a mask 50. As
illustrated in FIG. 40, the selective exposure forms a region of
acidic patterning resist 42 and regions of basic patterning resist
41. As discussed above with regard to FIG. 19B, acid may diffuse
from the acidic marker material 32 into a proximate segment of the
patterning material 40, i.e., the overlying segment of acidic
patterning resist 42, to enhance the acidity of the proximate
segment of acidic patterning resist 42. Therefore, the transfer of
acid from the acidic marker material 32 to the proximate segment of
the patterning resist 40 may encourage development of the acidic
patterning resist 42 proximate to the acidic marker material
32.
[0087] As illustrated in FIG. 41, following development with a
positive tone developer, selective for the acidic patterning resist
42, including the acid-enhanced segment proximate to the acidic
marker material 32, an array of aligned, elongate resist features
4100 is formed from the remaining basic patterning resist 41.
Because the acidic marker material 32 transferred acid to the
proximate segment of the patterning resist 40 to encourage the
development of the proximate segment, segments of the basic
patterning resist 41 may not overly the boundary 19 marked by the
acidic marker material 32, discouraging unwanted overlength
elongate resist features, such as those illustrated in FIG. 28.
Rather, each of the elongate features of the array 4100 may
terminate proximate to the border 19, e.g., near a proximate edge
of the acidic marker material 32.
[0088] FIGS. 42 through 45 illustrate a method of forming an array
of aligned elongate resist features using negative tone development
and basic chemical proximity correction to segments of unexposed
patterning resist. With reference to FIG. 42, a basic marker
material 31 may be formed in a trench 21 defined in the base
material 10. With reference to FIG. 43, a patterning resist 40 may
be formed thereover and selectively exposed using a mask 50. As
illustrated in FIG. 44, the selective exposure forms regions of
acidic patterning resist 42 and a region of basic patterning resist
41. As discussed above with regard to FIG. 25B, base may diffuse
from the basic marker material 31 into proximate segment of the
patterning material 40, i.e., the overlying segment of basic
patterning resist 41, to decrease the acidity of the proximate
segment of basic patterning resist 41. Therefore, transfer of base
from the basic marker material 31 to the proximate segment of the
patterning resist 40 may encourage development of the basic
patterning resist 41 proximate to the basic marker material 31.
[0089] As illustrated in FIG. 45, following development with a
negative tone developer, selective for the basic patterning resist
41, including the base-enhanced segment proximate to the basic
marker material 31, an array of aligned, elongate resist features
4500 is formed from the remaining acidic patterning resist 42.
Because the basic marker material 31 transferred base to the
proximate segment of the patterning resist 40 to encourage
development of the proximate segment, segments of the acidic
patterning resist 42 may not overly the boundary 19 marked by the
basic marker material 31, discouraging unwanted overlength elongate
resist features, such as those illustrated in FIG. 28. Rather, each
of the elongate features of the array 4500 may terminate proximate
to the border 19, e.g., near a proximate edge of the basic marker
material 31.
[0090] Accordingly, disclosed is a method of forming an array of
aligned elongate resist feature, the method comprising forming a
discrete feature of a marker material supported by a base material.
A patterning resist is formed over the base material. At least one
of an acid and a base is transferred from the marker material to a
region of the patterning resist proximate to the discrete feature
of the marker material to increase or decrease developability of
the region of the patterning resist relative to another region of
the patterning resist. The patterning resist is selectively exposed
and developed to define an array of elongate resist features. A
plurality of the elongate resist features of the array terminate in
substantially alignment proximate to the discrete feature of the
marker material.
[0091] Chemical proximity correction techniques of the present
disclosure may also be used to effectively convert an exposed,
acidic segment of resist to a basic segment or to effectively
convert an unexposed, basic segment of resist to an acidic segment,
chemically altering the developability of the segment. Therefore,
segments masked for exposure may be chemically converted to exhibit
developability similar to that of unexposed regions, and segments
masked not to be exposed may be chemically converted to exhibit
developability similar to that of exposed regions.
[0092] FIGS. 46 through 50 illustrate a method of forming an
interrupted resist feature using an uninterrupted mask, a positive
tone development, and acidic chemical proximity correction to a
segment of unexposed patterning resist. The method of FIGS. 46
through 50 is similar to that described above with regard to FIGS.
3 through 8B with the exception that the marker material 30 is
formulated as an acidic marker material 32. As such, with reference
to FIG. 48, acid from the acidic marker material 32 may be
transferred to a lower surface of a segment of the patterning
material, i.e., a proximate segment of unexposed, basic patterning
resist 41, to encourage development and removal by the positive
tone developer. Such an acidic marker material 32 may be formulated
to include large amounts of acid so as to accommodate substantial
transfer of acid from the acidic marker material 32 to the
proximate segment of basic patterning resist 41 to accomplish an
effective conversion of the proximate segment from basic patterning
resist 41 to acidic patterning resist 42, as illustrated in FIG.
49. Therefore, the acidic chemical proximity correction allows for
formation of an interrupted resist feature 5000, as illustrated in
FIG. 50, though an uninterrupted mask, e.g., mask 50 (FIG. 47) was
used to selectively expose the patterning resist 40.
[0093] In some embodiments, use of a conventional masking process
or conventional exposure process may result in exposure of a
segment of the patterning resist meant to remain unexposed. If it
is known that a particular resist pattern to be form is vulnerable
at such a region, the acidic chemical proximity correction
described above may be used to effectively convert an unexposed
segment of patterning resist, i.e., a segment of basic patterning
resist 41, into an effectively exposed segment of patterning
resist, i.e., a segment of acidic patterning resist 42. Thereafter,
in development, the converted segment may be developed, or not
developed, depending on the developer used, along with other
segments of acidic patterning resist 42.
[0094] FIG. 51 illustrates an interrupted resist feature formed
using an uninterrupted mask, a negative tone development, and basic
chemical proximity correction to a segment of unexposed resist. The
method used to form an interrupted resist feature 5100, illustrated
in FIG. 51, may be similar to that described above with regard to
FIGS. 9 through 14B, except that the marker material 30 is
formulated as a basic marker material 31. As such, base from the
basic marker material 31 may be transferred to a proximate segment
of patterning resist 40, i.e., a proximate segment of exposed,
acidic patterning resist 42, to encourage development and removal
by a negative tone developer. Such a basic marker material 31 may
be formulated to include large amounts of base so as to accommodate
substantial transfer of base from the basic marker material 31 to
the proximate segment of acidic patterning resist 42 to accomplish
an effective conversion of the acidic patterning resist 42 into
basic patterning resist 41. Thereafter, the base-converted segment
of basic patterning resist 41 may be developed along with the other
segments of basic patterning resist 41, forming the interrupted
resist feature 5100, despite using an uninterrupted mask, e.g.,
mask 50 (FIG. 12B).
[0095] In some embodiments, use of a conventional masking process
or conventional exposure process may result in exposure of a
segment of the patterning resist that was meant to remain
unexposed. If it is known that a particular resist pattern to be
formed is vulnerable at such a region, the basic chemical proximity
correction described above may be used to effectively convert an
exposed segment of patterning resist, e.g., a segment of acidic
patterning resist 42, into an effectively unexposed segment of
patterning resist, i.e., a segment of basic patterning resist 41.
Thereafter, in development, the converted segment may be developed,
or not developed, depending on the developer used, along with other
segments of basic patterning resist 41.
[0096] FIG. 52 illustrates an uninterrupted resist feature formed
using an interrupted mask, a positive tone development, and basic
chemical proximity correction to a segment of exposed resist. The
method used to form an uninterrupted resist feature 5200,
illustrated in FIG. 52, may be similar to that described above with
regard to FIGS. 15 through 20B, except that the marker material 30
is formulated as basic marker material 31. The basic marker
material 31 diffuses base into a proximate segment of acidic
patterning resist 42, e.g., a segment of unintentionally-exposed
patterning resist 40, to effectively convert the proximate segment
to basic patterning resist 41, i.e., effectively unexposed
patterning resist 40. Thus, the basic marker material 31
discourages development of the proximate segment in a subsequent
positive tone development process, resulting in the uninterrupted
resist feature 5200, despite the initial formation of interrupted
regions of basic patterning resist 41.
[0097] FIG. 53 illustrates an uninterrupted resist feature formed
using an interrupted mask, a negative tone development, and acidic
chemical proximity correction to a segment of exposed resist. The
method used to form an uninterrupted resist feature 5300,
illustrated in FIG. 53, may be similar to that described above with
regard to FIGS. 21 through 26B, except that the marker material 30
is formulated as acidic marker material 32. The acidic marker
material 32 transfers acid to a proximate segment of basic
patterning resist 41, e.g., a segment of unintentionally unexposed
patterning resist 40, to effectively convert the proximate segment
to acidic patterning resist 42, i.e., effectively exposed
patterning resist 40. Thus, the acidic marker material 32
discourages development of the proximate segment in a subsequent
negative tone development process, resulting in the uninterrupted
resist features 5300, despite the initial formation of interrupted
regions of acidic patterning resist 42.
[0098] In other embodiments, a combination of acidic chemical
proximity correction and base chemical proximity correction
techniques may be utilized simultaneously. In still other
embodiments, acidic chemical proximity correction, basic chemical
proximity correction, or both may be used to discourage development
of one segment of patterning resist 40 while simultaneously
encouraging development of another segment of patterning resist
40.
[0099] Accordingly, disclosed is a method of forming a pattern in a
resist, the method comprising forming a resist on a base material
and selectively exposing an upper surface of the resist to define
an acidic resist region and a non-acidic resist region. Acid is
added to a lower surface of a segment of the non-acidic resist
region to convert the segment of the non-acidic resist region into
an acidic resist segment, leaving another segment of the non-acidic
resist region. The resist is developed with a developer selective
for one of the acidic resist segment and the another segment of the
non-acidic resist region over another of the acidic resist segment
and the another segment of the non-acidic resist region.
[0100] Also disclosed is a method of forming a pattern in a resist,
the method comprising forming a resist on a base material and
selectively exposing an upper surface of the resist to define an
acidic resist region and a non-acidic resist region. Base is added
to a lower surface of a segment of the acidic resist region to
convert the segment of the acidic resist region into a non-acidic
resist segment, leaving another segment of the acidic resist
region. The resist is developed with a developer selective for one
of the non-acidic resist segment and the another segment of the
acidic resist region over another of the non-acidic resist segment
and the another segment of the acidic resist region.
[0101] The foregoing methods may be useful to pattern a resist
material in an intricate pattern that would otherwise be vulnerable
to line breaks, line merges, or misalignments is implemented
according to conventional processes.
[0102] While the present disclosure is susceptible to various
modifications and alternative forms in implementation thereof,
specific embodiments have been shown by way of example in the
drawings and have been described in detail herein. However, the
present disclosure is not intended to be limited to the particular
forms disclosed. Rather, the present disclosure encompasses all
modifications, combinations, equivalents, variations, and
alternatives falling within the scope of the present disclosure as
defined by the following appended claims and their legal
equivalents.
* * * * *